Liquid crystal display devices have the features of, e.g., being electrically operated at a low voltage and operated with a low electric power, having color display and providing a display area in the range of from several millimeters square to tens meters square. In recent years, research and development have been in rapid progress to put to practical use liquid crystal display devices with color display and large-size display. These liquid crystal display devices are required to have a high picture element density, the formation of fine patterns of transparent electrode having a pitch of about 100 .mu.m, a high reliability, etc.
An electrode plate having a transparent electrode formed on a color filter in a color liquid crystal display device is excellent in the operability of liquid crystal and the quality of display. In such display devices, an overcoat of organic resin is usually formed between a color filter and a transparent electrode in patterning the transparent electrode by etching.
The overcoat is formed to make the color filter flat and to protect the filter, and thus must have a high adhesion to a transparent electrode, compatibility with the process of patterning a transparent electrode, resistance to heat, resistance to acids, resistance to alkalis, etc.
Conventional overcoats are usually formed from a resin of the same type as used for a color filter in view of the adhesion to the color filter. However, substantially all species of resins used for color filters have the drawbacks of, for example, exhibiting low resistance to heat in the formation of transparent electrode, thereby causing wrinkles and blisters.
Known among methods of forming a patterned overcoat is a method in which an overcoat is produced from a photosensitive resin and then developed with an organic solvent. This method employs an organic solvent as a developer, which is difficult to handle and makes the working environment unfavorable. Also known is a method in which an overcoat of photosensitive resin is exposed to light and developed with an aqueous solution of alkali. The overcoats formed from photosensitive resins conventionally used in such method are not fully satisfactory in properties such as resistance to water and heat.